package com.tys.algorithm.advanced.test.class11;

/*
二叉树结构如下定义：
Class Node{
V value;
Node left; //左孩子
Node right; //右孩子
Node parent; //父节点
}
给你二叉树中的某个节点，返回该节点的后继节点
*/
public class Code06_SuccessorNode {

    public static class Node {
        public int value;
        public Node left; //左孩子
        public Node right; //右孩子
        public Node parent; //父节点

        public Node(int data) {
            this.value = data;
        }
    }

    //找后继
    public static Node getSuccessorNode(Node node) {
        if (node == null) { //为空返回
            return node;
        }

        if (node.right != null) { //有右树
            //找右树的最左孩子：后继
            return getLeftMost(node.right);
        } else { // 无右子树
            Node parent = node.parent; //拿到父节点
            //parent不为空，node是parent的右孩子
            while (parent != null && parent.right == node) { // 当前节点是其父亲节点右孩子
                node = parent; //右孩子移动到父
                parent = node.parent; //重新赋值给parent
            }
            return parent; //后继
        }
    }

    //找最左的左孩子
    public static Node getLeftMost(Node node) {
        if (node == null) {
            return node;
        }
        while (node.left != null) {
            node = node.left;
        }
        return node;
    }

    public static void main(String[] args) {
        Node head = new Node(6);
        head.parent = null;
        head.left = new Node(3);
        head.left.parent = head;
        head.left.left = new Node(1);
        head.left.left.parent = head.left;
        head.left.left.right = new Node(2);
        head.left.left.right.parent = head.left.left;
        head.left.right = new Node(4);
        head.left.right.parent = head.left;
        head.left.right.right = new Node(5);
        head.left.right.right.parent = head.left.right;
        head.right = new Node(9);
        head.right.parent = head;
        head.right.left = new Node(8);
        head.right.left.parent = head.right;
        head.right.left.left = new Node(7);
        head.right.left.left.parent = head.right.left;
        head.right.right = new Node(10);
        head.right.right.parent = head.right;

        Node test = head.left.left;
        System.out.println(test.value + " next: " + getSuccessorNode(test).value);
        test = head.left.left.right;
        System.out.println(test.value + " next: " + getSuccessorNode(test).value);
        test = head.left;
        System.out.println(test.value + " next: " + getSuccessorNode(test).value);
        test = head.left.right;
        System.out.println(test.value + " next: " + getSuccessorNode(test).value);
        test = head.left.right.right;
        System.out.println(test.value + " next: " + getSuccessorNode(test).value);
        test = head;
        System.out.println(test.value + " next: " + getSuccessorNode(test).value);
        test = head.right.left.left;
        System.out.println(test.value + " next: " + getSuccessorNode(test).value);
        test = head.right.left;
        System.out.println(test.value + " next: " + getSuccessorNode(test).value);
        test = head.right;
        System.out.println(test.value + " next: " + getSuccessorNode(test).value);
        test = head.right.right; // 10's next is null
        System.out.println(test.value + " next: " + getSuccessorNode(test));
    }

}
